Targeting HMGB1 Increased the Sensitivity of MM Cells to Chemotherapy

Background ：Multiple myeloma (MM) is an malignant disease of clonal plasma cell hyperplasia, which incidence is increasing in recent years. Chemotherapy is the main method to treat MM, but because of drug resistance, MM is still an incrurable disease. High-mobility group box 1 protein (HMGB1) is a chromatin associated nuclear protein, which participated in DNA damage repair , rearrangement, and it also as an extracellular damage associated molecular pattern molecule(DAMP) involved in inflammation, neoplastic progression, angiogenesis, invasion and metastasiss and drug resistance of kinds of tumor cells. There’s no research about the role of HMGB1 in multiple myeloma before.

Methods: First, We detected HMGB1 mRNA and protein expression level in MM cell lines and primary MM cells by semiquantitative real time-polymerase chain (qRT-PCR)and western blot respectively. The concentration of HMGB1 in the culture supernatants of MM cell lines and primary MM cells was detected by ELISA. Second, we constructed Lentivirus vector with HMGB1 shRNA, infected the lentivirus to MM cells to knockdown HMGB1 expression. Then Chemo-drugs (ADM, quercetin and bortezomib) were added to MM cells, flow cytometry was used for the detection of cell apoptosis.

Results:MM cell line and primary MM cell all express HMGB1 with high level. The concentration of HMGB1 in the MM cell supernatants was significantly elevated after chemotherapy treatment compared with untreated cells(p<0.05), and HMGB1 in MM patients’ bone marrow supernatants was very high. Knockdown of HMGB1 increased 8226 and ARP-1 cell apoptosis induced by ADM and quercetin (NC shRNA VS HMGB1 shRNA, p<0.05), but there’s no significant difference induced by bortezomib.

Conclusions: Our study showed that the concentration of HMGB1 in the MM cell supernatants was significantly elevated after chemotherapy treatment. Further more, knockdown of HMGB1 by shRNA increased the sensitivity of MM cells to chemotherapy.